For firefighters working on the fireground, the most obvious concern for personal safety is protection against burn injury. Firefighters' turnout gear, which typically consists of matching coat and pants, is designed primarily to prevent the wearer from sustaining a serious burn. The National Fire Protection Association (NFPA) publishes a minimum performance standard for firefighters' turnout gear. This standard is recognized industry-wide as the overall guideline for identifying the minimum level of performance for turnout gear and the fabrics from which they are constructed. For any gear to be labelled compliant with NFPA 1971, the fabrics in that gear must be subjected to many stringent tests, most related to flammability.
NFPA compliant turnout gear or garments are comprised of three layers: an outer shell, an intermediate moisture barrier, and a thermal barrier lining. The outer shell is usually a woven fabric made from flame resistant fibers such as an aramid such as those sold under the trademarks NOMEX.RTM. and KEVLAR.RTM. by Dupont. The outer shell is considered a firefighter's first line of defense. Not only should it resist flame, but it needs to be tough and durable so as not to be torn, abraded, or snagged during normal firefighting activities.
The moisture barrier, while also flame resistant, is present to keep water from coming in and saturating the turnout gear. Excess moisture entering the gear from the outside would laden the firefighter with extra weight and increase his or her load. A suitable moisture barrier is a layer of GORE-TEX.RTM. material on a substrate of NOMEX.RTM..
The thermal barrier is flame resistant and offers the bulk of the thermal protection afforded by the ensemble. A traditional thermal barrier is a batting made of a nonwoven fabric of flame resistant fibers quilted to a lightweight woven face cloth also made of flame resistant fibers. The batting may be either a single layer of needle-punch nonwoven fabric or multiple layers of spun lace nonwoven fabric. The face cloth is commonly quilted to the batting in a cross-over or chicken wire pattern. The end product is a relatively thick, inflexible fabric that will not stretch due to the limitation placed on it by the face cloth. The quilted thermal barrier is the innermost layer of the firefighter's garment and the face cloth may be next to the firefighter's skin if he or she is not wearing a station uniform or is wearing a station uniform with short sleeves.
The combination of the batting and the face cloth commonly is called the thermal barrier lining and it typically attaches to the inside of the garment by snaps so that it is removable to be easily washed or otherwise cleaned. Often times the lining also attaches to the garment by means of areas of hook-and-loop fasteners such as that sold under the trademark VELCRO.RTM.. The garment itself often is sealed by means of hook-and-loop fasteners rather than, for example, a zipper.
A problem with many linings currently sold and used is that the face cloth of the lining is rough and when the firefighter dons the jacket or pants the firefighter's street clothes or station uniform bunch up under the firefighter's garment. A face cloth having a smooth, slick surface can prevent this from happening because the cloth will slide over the station uniform and not cause it to bunch up. A rough face cloth also creates friction with the station uniform underneath it, making it even more difficult for the firefighter to move inside his or her gear. This increased exertion could lead to heat stress more quickly and severely.
One currently available face cloth is made from a fabric of all spun yarns of 100% poly(m-phenyleneisophthalamide). The yarns are woven into a fabric having a "pajama check" pattern. An aqueous finish is applied to the fabric which renders the fabric wickable. This finish includes an ethoxylated ester, a binder, and an inorganic salt catalyst and is applied by a pad-nip-tenter system. This face cloth has a rough texture and often leads to the station uniform bunching up under the garment. However, this is one of the least costly types of face cloth.
Another fabric currently used as a face cloth is also 100% poly(m-phenyleneisophthalamide) but it is a twill weave of spun warp yarns and filament filling yarns. The twill weave results in more filament yarns than spun yarns on one surface of the face cloth. Filament yarns are smoother than spun yarns and so this face cloth has one surface that is substantially slicker and smoother than the all spun yarn cloth described above. However, this spun/filament cloth has the problem that it is easily "picked" by the j-hooks of the hook-and-loop fasteners and by other relatively sharp items. The face cloth will become frayed and begin to present an unaesthetic appearance.
Still another type of face cloth currently on the market is made from 100% poly(m-phenyleneisophthalamide) and is a plain weave of all filament yarns. This fabric made of all filament yarns has the problem that the warp and filling yarns are slick and slide against one another. Thus, locations where the warp and filling yarns intersect are not particularly stable. This instability is passed on to the seam structures which easily deform when stressed. Also the fabric has a propensity to ravel at cut edges, a propensity which is aggravated during the cutting and sewing operations required to render the fabric into a useful face cloth. To solve this problem, all filament fabric requires a backcoating, usually a polyurethane, that imparts stability to the fabric by binding the yarns to one another. A side effect of the backcoating is that the fabric is made water repellent. This is a disadvantage for a face cloth because any moisture deposited on the face cloth from sweat, for example, remains on the surface of the cloth facing the firefighter and is not wicked into the interior of the face cloth. This can result in discomfort and, perhaps, scalding of the firefighter's skin. This face cloth does not, however, have the problem of being "picked" by hook-and-loop fasteners, probably because of the backcoating.
Spun yarns are manufactured from fibers having a fairly short length, about one (1) to one and one-half (11/2) inches. The fibers are spun and twisted tightly together into a yarn. Filament yarns are made from extruded filaments. A filament yarn can be only one filament but typically has multiple filaments gently twisted into a multifilament yarn. Some filament yarns have a slight twist but not as much as spun yarns. Filament yarns are smoother than spun yarns and have a disadvantage in that they will not readily accept a finish or binder applied to a fabric made therefrom. It is believed that finish chemicals do not actually penetrate the filaments but rather reside between individual filaments. Spun yarns have a greater surface area and more interstices creating more places for finish to reside.
It is apparent from the above discussion that there is a need for a face cloth which combines a slick and smooth surface with hook-and-loop fastener compatibility and moisture wickability.